const mongoose = require('mongoose');
const fs = require('fs').promises;
const path = require('path');
const { exec } = require('child_process');
const { promisify } = require('util');

const execAsync = promisify(exec);

// Atlas MongoDB connection string
const MONGODB_URI = 'mongodb+srv://nothingyu:wSg3lbO1PkHiRMq9@sandbox.ecysggv.mongodb.net/test?retryWrites=true&w=majority&appName=sandbox';

// Connect to MongoDB Atlas
const connectDB = async () => {
  try {
    await mongoose.connect(MONGODB_URI);
    console.log('✅ Connected to MongoDB Atlas');
  } catch (error) {
    console.error('❌ MongoDB connection error:', error);
    process.exit(1);
  }
};

// Comprehensive Backup System (Data + Code)
const comprehensiveBackup = {
  // Create comprehensive backup
  async createComprehensiveBackup() {
    try {
      const timestamp = new Date().toISOString().replace(/[:.]/g, '-');
      const backupName = `comprehensive-backup-${timestamp}`;
      
      console.log(`🚀 Creating comprehensive backup: ${backupName}`);
      
      // Create backup directory
      const backupDir = path.join(__dirname, 'backups', backupName);
      await fs.mkdir(backupDir, { recursive: true });
      
      // 1. BACKUP DATABASE DATA
      console.log('📊 Backing up database data...');
      const dbBackup = await this.backupDatabase(backupDir);
      
      // 2. BACKUP CODE FILES
      console.log('💻 Backing up code files...');
      const codeBackup = await this.backupCodeFiles(backupDir);
      
      // 3. BACKUP CONFIGURATION
      console.log('⚙️ Backing up configuration...');
      const configBackup = await this.backupConfiguration(backupDir);
      
      // 4. CREATE BACKUP MANIFEST
      console.log('📋 Creating backup manifest...');
      const manifest = {
        backupName,
        timestamp: new Date(),
        type: 'comprehensive',
        data: {
          database: dbBackup,
          code: codeBackup,
          configuration: configBackup
        },
        totalSize: await this.calculateBackupSize(backupDir),
        version: '1.0'
      };
      
      await fs.writeFile(path.join(backupDir, 'manifest.json'), JSON.stringify(manifest, null, 2));
      
      // 5. SAVE BACKUP RECORD TO DATABASE
      const backupRecord = {
        backupName,
        timestamp: new Date(),
        type: 'comprehensive',
        location: backupDir,
        size: manifest.totalSize,
        status: 'created'
      };
      
      await mongoose.connection.db.collection('backups').insertOne(backupRecord);
      
      console.log(`✅ Comprehensive backup created: ${backupName}`);
      console.log(`📊 Database records: ${dbBackup.totalRecords}`);
      console.log(`💻 Code files: ${codeBackup.fileCount}`);
      console.log(`💾 Total size: ${(manifest.totalSize / 1024 / 1024).toFixed(2)} MB`);
      
      return backupName;
      
    } catch (error) {
      console.error('❌ Error creating comprehensive backup:', error);
      throw error;
    }
  },
  
  // Backup database data
  async backupDatabase(backupDir) {
    const collections = ['subtitles', 'sourcetexts', 'submissions', 'users', 'backups'];
    const dbData = {};
    let totalRecords = 0;
    
    for (const collection of collections) {
      try {
        const data = await mongoose.connection.db.collection(collection).find({}).toArray();
        dbData[collection] = data;
        totalRecords += data.length;
        console.log(`  📦 Exported ${data.length} records from ${collection}`);
      } catch (error) {
        console.warn(`  ⚠️ Could not export ${collection}:`, error.message);
      }
    }
    
    const dbBackupPath = path.join(backupDir, 'database.json');
    await fs.writeFile(dbBackupPath, JSON.stringify(dbData, null, 2));
    
    return {
      totalRecords,
      collections: Object.keys(dbData),
      filePath: dbBackupPath
    };
  },
  
  // Backup code files
  async backupCodeFiles(backupDir) {
    const codeDir = path.join(backupDir, 'code');
    await fs.mkdir(codeDir, { recursive: true });
    
    // Define important code directories and files
    const codePaths = [
      // Backend code
      { src: path.join(__dirname), dest: 'backend' },
      // Frontend code (relative to backend)
      { src: path.join(__dirname, '../frontend'), dest: 'frontend' },
      // Root configuration
      { src: path.join(__dirname, '../../'), dest: 'root' }
    ];
    
    let fileCount = 0;
    
    for (const codePath of codePaths) {
      try {
        if (await this.pathExists(codePath.src)) {
          await this.copyDirectory(codePath.src, path.join(codeDir, codePath.dest));
          const count = await this.countFiles(codePath.src);
          fileCount += count;
          console.log(`  💻 Copied ${count} files from ${codePath.dest}`);
        }
      } catch (error) {
        console.warn(`  ⚠️ Could not backup ${codePath.dest}:`, error.message);
      }
    }
    
    return {
      fileCount,
      directories: codePaths.map(p => p.dest),
      location: codeDir
    };
  },
  
  // Backup configuration
  async backupConfiguration(backupDir) {
    const configDir = path.join(backupDir, 'config');
    await fs.mkdir(configDir, { recursive: true });
    
    const configFiles = [
      'package.json',
      'package-lock.json',
      'Dockerfile',
      'docker-compose.yml',
      'nginx.conf',
      '.gitignore'
    ];
    
    let configCount = 0;
    
    for (const configFile of configFiles) {
      try {
        const srcPath = path.join(__dirname, configFile);
        if (await this.pathExists(srcPath)) {
          const destPath = path.join(configDir, configFile);
          await fs.copyFile(srcPath, destPath);
          configCount++;
          console.log(`  ⚙️ Copied ${configFile}`);
        }
      } catch (error) {
        console.warn(`  ⚠️ Could not copy ${configFile}:`, error.message);
      }
    }
    
    return {
      fileCount: configCount,
      files: configFiles,
      location: configDir
    };
  },
  
  // Helper functions
  async pathExists(path) {
    try {
      await fs.access(path);
      return true;
    } catch {
      return false;
    }
  },
  
  async copyDirectory(src, dest) {
    await fs.mkdir(dest, { recursive: true });
    const entries = await fs.readdir(src, { withFileTypes: true });
    
    for (const entry of entries) {
      const srcPath = path.join(src, entry.name);
      const destPath = path.join(dest, entry.name);
      
      if (entry.isDirectory()) {
        await this.copyDirectory(srcPath, destPath);
      } else {
        await fs.copyFile(srcPath, destPath);
      }
    }
  },
  
  async countFiles(dir) {
    let count = 0;
    const entries = await fs.readdir(dir, { withFileTypes: true });
    
    for (const entry of entries) {
      const fullPath = path.join(dir, entry.name);
      
      if (entry.isDirectory()) {
        count += await this.countFiles(fullPath);
      } else {
        count++;
      }
    }
    
    return count;
  },
  
  async calculateBackupSize(backupDir) {
    const { stdout } = await execAsync(`du -sb "${backupDir}" | cut -f1`);
    return parseInt(stdout.trim());
  },
  
  // List comprehensive backups
  async listComprehensiveBackups() {
    try {
      console.log('📋 Available comprehensive backups:');
      
      const backupCollection = mongoose.connection.db.collection('backups');
      const backups = await backupCollection.find({ type: 'comprehensive' }).sort({ timestamp: -1 }).toArray();
      
      if (backups.length === 0) {
        console.log('  No comprehensive backups found');
      } else {
        backups.forEach(backup => {
          const date = new Date(backup.timestamp).toLocaleString();
          const size = (backup.size / 1024 / 1024).toFixed(2);
          console.log(`  📦 ${backup.backupName} (${size} MB, ${date})`);
        });
      }
      
    } catch (error) {
      console.error('❌ Error listing backups:', error);
    }
  },
  
  // Restore from comprehensive backup
  async restoreFromBackup(backupName) {
    try {
      console.log(`🔄 Restoring from comprehensive backup: ${backupName}`);
      
      const backupDir = path.join(__dirname, 'backups', backupName);
      const manifestPath = path.join(backupDir, 'manifest.json');
      
      if (!await this.pathExists(manifestPath)) {
        throw new Error('Backup manifest not found');
      }
      
      const manifest = JSON.parse(await fs.readFile(manifestPath, 'utf8'));
      console.log('📋 Backup manifest:', manifest);
      
      // Restore database
      console.log('📊 Restoring database...');
      await this.restoreDatabase(backupDir);
      
      // Restore code (optional - user confirmation)
      console.log('💻 Code restoration available');
      console.log('⚠️ Code restoration will overwrite existing files');
      console.log('   Run: node restore-code.js <backup-name> to restore code');
      
      console.log(`✅ Database restoration completed: ${backupName}`);
      
    } catch (error) {
      console.error('❌ Error restoring from backup:', error);
    }
  },
  
  // Restore database only
  async restoreDatabase(backupDir) {
    const dbBackupPath = path.join(backupDir, 'database.json');
    const dbData = JSON.parse(await fs.readFile(dbBackupPath, 'utf8'));
    
    for (const [collection, data] of Object.entries(dbData)) {
      try {
        // Clear existing data
        await mongoose.connection.db.collection(collection).deleteMany({});
        
        // Insert backup data
        if (data.length > 0) {
          await mongoose.connection.db.collection(collection).insertMany(data);
        }
        
        console.log(`  ✅ Restored ${data.length} records to ${collection}`);
      } catch (error) {
        console.error(`  ❌ Error restoring ${collection}:`, error.message);
      }
    }
  }
};

// Main function
const main = async () => {
  try {
    console.log('🚀 Starting comprehensive backup system...');
    
    // Create comprehensive backup
    const backupName = await comprehensiveBackup.createComprehensiveBackup();
    
    // List backups
    await comprehensiveBackup.listComprehensiveBackups();
    
    console.log('\n🎉 Comprehensive backup system ready!');
    console.log('\n📋 Available functions:');
    console.log('  - createComprehensiveBackup(): Backup data + code');
    console.log('  - listComprehensiveBackups(): List all backups');
    console.log('  - restoreFromBackup(name): Restore database');
    console.log('  - restoreCode(name): Restore code files (separate script)');
    
    console.log('\n⏰ To set up automated comprehensive backups:');
    console.log('  1. Add to crontab: 0 2 * * * cd /path/to/backend && node comprehensive-backup.js');
    console.log('  2. Or run manually: node comprehensive-backup.js');
    
  } catch (error) {
    console.error('❌ Error in comprehensive backup system:', error);
  } finally {
    await mongoose.disconnect();
    console.log('🔌 Disconnected from MongoDB');
  }
};

// Run the system
connectDB().then(() => {
  main();
});